# CVE-2026-33747: BuildKit vulnerable to malicious frontend causing file escape outside of storage root > A malicious BuildKit frontend can write files outside the storage root, requiring the use of untrusted custom frontends. - **Severity:** High 8.4 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Local or same network only - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 27 Mar 2026 - **Updated:** 27 Mar 2026 - **Also known as:** BELL-CVE-2026-33747, CLEANSTART-2026-DU09908, CLEANSTART-2026-IP63543, CLEANSTART-2026-QH82064, CLEANSTART-2026-TB67127, DEBIAN-CVE-2026-33747, ECHO-32a1-300a-79e3, GHSA-4c29-8rgm-jvjj, GO-2026-4858, MINI-2mhv-9v7r-mmv4, MINI-2rpf-jgj3-hq7f, MINI-3482-48j6-xmjr, MINI-427q-22x5-mfwm, MINI-5ghw-q47f-7qr9, MINI-67p4-ph8f-rvr3, MINI-7cpr-g2r5-rgrh, MINI-f5p9-jm3h-548x, MINI-f8x5-56mj-xwwv, MINI-fjrv-387j-xgw9, MINI-h8hm-4mx3-7wvx, MINI-j6rw-fvvw-hjq8, MINI-m27m-qj45-53qg, MINI-m72g-wjgp-gx9m, MINI-m8wj-h3vw-7vxh, MINI-mhhw-pj25-38h5, MINI-mp4m-q48h-p7vc, MINI-mw6c-cjq6-hpmf, MINI-mxff-76fc-3x3p, MINI-pqjc-6w4f-wm73, MINI-qm96-2mqx-8rgc, MINI-rm77-6g6f-mfv3, MINI-v9fm-7376-2r46, MINI-vc69-rjh8-9wcv, MINI-vq7v-4pw9-cww8, ROOT-APP-GOBINARY-CVE-2026-33747, UBUNTU-CVE-2026-33747, USN-8230-1, openSUSE-SU-2026:10456-1, openSUSE-SU-2026:10472-1 ## What is CVE-2026-33747? CVE-2026-33747 is a high-severity path traversal vulnerability in moby buildkit, published on 27 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim. ### Official description BuildKit is a toolkit for converting source code to build artifacts in an efficient, expressive and repeatable manner. Prior to version 0.28.1, when using a custom BuildKit frontend, the frontend can craft an API message that causes files to be written outside of the BuildKit state directory for the execution context. The issue has been fixed in v0.28.1. The vulnerability requires using an untrusted BuildKit frontend set with `#syntax` or `--build-arg BUILDKIT_SYNTAX`. Using these options with a well-known frontend image like `docker/dockerfile` is not affected. Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory) ## Which versions are affected by CVE-2026-33747? 3 open source packages ship an affected version, including github.com/moby/buildkit. It affects 1 product. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `github.com/moby/buildkit` | Go | All versions | 0.28.1 | | `github.com/moby/buildkit` | Go | All versions | 0.28.1 | | `github.com/moby/buildkit` | Go | All versions | 0.28.1 | | `conftest` | openSUSE:Tumbleweed | All versions | 0.67.1-2.1 | | `tailscale` | openSUSE:Tumbleweed | All versions | 1.96.4-1.1 | Products: Mobyproject Buildkit. ## How do I fix CVE-2026-33747? Upgrade github.com/moby/buildkit to 0.28.1 or later. ## Is CVE-2026-33747 being exploited? There is no known exploitation of CVE-2026-33747 in the wild and no public exploit code. ## Other vulnerabilities in moby buildkit - [CVE-2024-23652](https://insights.sbomify.com/CVE-2024-23652/): BuildKit possible host system access from mount stub cleaner (critical 10.0) - [CVE-2024-23653](https://insights.sbomify.com/CVE-2024-23653/): BuildKit interactive containers API does not validate entitlements check (critical 9.8) - [CVE-2024-23651](https://insights.sbomify.com/CVE-2024-23651/): BuildKit possible race condition with accessing subpaths from cache mounts (high 8.7) - [CVE-2026-33748](https://insights.sbomify.com/CVE-2026-33748/): BuildKit Git URL subdir component can cause access to restricted files (high 8.2) - [CVE-2026-15789](https://insights.sbomify.com/CVE-2026-15789/): Malicious client can bypass destination directory validation on local sources upload (medium 6.9) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-33747 and fix it if it is affected. What it is: CVE-2026-33747 is a high-severity path traversal vulnerability in moby buildkit, published on 27 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim. Exploitation: There is no known exploitation of CVE-2026-33747 in the wild and no public exploit code. Affected packages and fixed versions: - github.com/moby/buildkit (Go): affected all versions; fixed in 0.28.1 - github.com/moby/buildkit (Go): affected all versions; fixed in 0.28.1 - github.com/moby/buildkit (Go): affected all versions; fixed in 0.28.1 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-33747/ (Markdown: https://insights.sbomify.com/CVE-2026-33747/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33747 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33747 - OSV: https://osv.dev/vulnerability/CVE-2026-33747 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-33747/ Summaries are generated and may contain mistakes; the official description above is the record.